Leaf Spot is one of the most common diseases associated with turf grass. Leaf Spot is a disease caused by a fungus. This disease can cause a lawn to thin. In a worst-case scenario the spots appear at the base of the leaf blade. This can result in the loss of the blade and possibly the entire plant. When this occurs the disease is also known as "melting out".
WHEN DOES IT OCCUR:
Leaf Spot can be found on all types of grass but in our area it is generally found to affect bluegrass cultivars. It occurs as small spots on the blade and sheath. The spots may become bigger and change color from a purplish brown to a black. When the spots become so numerous, the leaf of the plant collapses. If the disease results in so much damage, the lawn will require serious rehabilitation. Where the disease is not so severe, the lawn takes on a brownish discoloration and mimics summer drought conditions.
As with many fungal diseases in lawns, Leaf Spot favors warm, wet weather. The fungus thrives on plants that are growing rapidly, so it is more evident in springtime and early summer. Because the disease loves the warm, wet weather, it is vital you water your lawn in the early morning. This gives the grass a chance to dry out during the day. Watering in the evening will only give the disease a better chance to establish itself. If the grass dies as a result of Leaf Spot, ensure you re-seed with a more resistant cultivar of bluegrass. Your local gardening center should be able to help you in this area.